Answer:
n=the whole number
n2=the square of the whole number
n2+n=the sum
proof:
n2+n the sum
n(n+1) factored
for all whole numbers n, n and n+1 are consecutive whole numbers
for any two consecutive whole numbers, one must be even and one must be odd
the product of an even number and an odd number is always an even number
therefore n2+n is an even number
Step-by-step explanation: